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UNITED STATES PATENT OFFICE.

JAMES F. HEYWARD, OF WILMINGTON, DELAWARE, ASSIGNOR TO THE DELAWARE AIR SPRING MANUFG. COMPY.

PNEUMATIC SPRING.

Specification of Letters Patent No. 13,248, dated July 16, 1855.

,side of the spring and Fig. 2, represents a transverse sectional View of the same.

The nature of my invention consists, in employing a fluid piston, playing in an air chamber of any form, in such a manner, that when the fluid piston is forced against the contained air, it will compress the same to such an extent as to cause the resistance of its elasticity to balance the force applied. This fluid piston being moved throiwh the intervention of any flexible inextensib e water-proof bottom, securely fastened to the lower margin of the air chamber.

To enable others skilled in the art to make and use my invention, I will proceed to clescribe its construction and operation.

A is a metallic cylinder open at the bottom, with a flange B, B, projecting from its lower margin. L is a thick sheet of india rubber, extending from outside to outside of the flange B, B, and closing the opening of the cylinder so as to render it water tight. The gum hasa considerable deviation downward from the plane of the mouth of the cylinder as shown in the drawing.

Gr is a sheet of leather or any other flexible inextensible material of the same dimensions and outline as the sheet of india rubber L, just described. Its use is merely to afiord support to the gum.

P is a rod passing through the center of the gum and leather bottom, with a shoulder inside and a nut outside, by means of which the gum and leather may be so compressed as to leave the vessel still perfectly watertight. The object of the rod P is to insure the movement upward in a straight line of the flexible bottom, which is effected by causing it to play in the hollow cylinder 0, which forms part of the top of the air chamber A.

R is an iron ring, drawn up by the bolts 1), b, pressing the india rubber and leather against the flange of the cylinder so as to render the whole watertight.

The space between the red line and gum, shows the position of the fluid piston, which moves upward, compressing the air in the top of the air chamber, whenever the flexible bottom is exposed to pressure.

H, is a tube passing through the flange .of the cylinder, communicating with the inside of the cylinder, through which the air 1s forced into it, by means of any air pump. The opening may be closed by any known arrangement of stop-cock, care however mustbe had, that its inner opening must always be below the level of the water sur' face constituting the piston.

Having thus fully described the nature of my improvement in pneumatic springs, what I claim therein as new and desire to secure by Letters Patent, is

The method of rendering available the elasticity of aeriform bodies in the construct1on of springs, bumpers &c., by employing a fluid piston to efi'ect their compression substantially as described.

J. F. HEYWARD.

WVitnesses:

THOS. H. UPPERMAN, CHAS. E. UPPERMAN. 

